High platelets: causes, symptoms and what to do

In the vast majority of cases, high platelets are your body reacting to something else: usually inflammation, an infection, a recent operation or low iron. Once the cause passes, they generally go back to normal. Only rarely does the marrow make too many on its own.

What high platelets mean

Your marrow makes more platelets when your body asks for them, for example during inflammation or when iron is short. Above your report’s limit, usually 400, it is called thrombocytosis.

That is why the first step is to show your report to your doctor, who looks for the cause and usually repeats the test. In one study, fewer than one in ten people with a count above 400 at the first test still had a high count at the re-check, eight months later.

What causes high platelets

The first ones are the most common.

High platelets: the symptoms

Usually none. Platelets that are high because of inflammation or low iron cause no symptoms of their own: if there are any, they come from the cause, like tiredness when iron is short.

In the rare marrow conditions, though, there can be headaches, problems with your sight, and burning, red hands and feet. In those cases the risk of thrombosis, meaning clots in the blood vessels, goes up too.

High platelets and iron

This is a common pairing. When iron is short, the marrow tends to make more platelets. That is why ferritin, your iron store, is checked too when platelets are high.

If iron is low, the cause should be found with your doctor, who also decides the treatment. Once iron is back to normal, platelets usually come down as well.

Which tests to read alongside it

These tests help find the cause.

What your result means

The upper end of the scale, in x10⁹/L. If your report prints the whole count, 400 thousand per mm³ is the same as 400.

How to lower high platelets

They come down when the cause goes away. Where to start:

When to worry

Talk to your doctor if:

With Rosa, platelets above 400 x10⁹/L are flagged to a doctor, usually with a repeat test.

Frequently asked questions

High platelets: should I worry? Usually not. Most of the time they are a response to inflammation, an infection or low iron, and they come down when the cause passes. Talk to your doctor, who will usually repeat the test.

Can high platelets be a sign of cancer? Usually not. Over forty, a count that stays above 400 at the re-check is linked to a higher risk of cancer, mostly lung or bowel. Even then, most of the time the cause is something else: that is why your doctor repeats the test and, if the count stays high, looks for it.

Do high platelets cause thrombosis? Usually not: when they are high because of inflammation or low iron, the risk is low. It matters more in the rare marrow conditions, which your doctor looks for if the count stays high with no clear cause.

When should they be checked again? Your doctor decides, usually within a few months, to see whether they stay high. After an infection it is best to wait until you have healed.

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